There are a number of speculations on this site on how Warren Buffett grants access to reporters. Here is something from the source:
FBN's Liz Claman on getting to know and interview Warren Buffett.
Click here to watch the video if you do not see the video player above.
Here a number of videos in which Buffett interviewed by Liz Claman. Sorry for the out-of-datedness, I can't control that.